The capacity and speed of communications systems may be increased by transmitting information in optical form over networks composed of optically transmissive nodes, fibers, waveguides, and the like. High capacity optical communications systems require that many optical signals be frequency division multiplexed in the components of an optical network. This requires that there be a way of conveniently producing electromagnetic energy at many different frequencies. An ideal device for producing optical energy useful in an optical communications system is a laser. Until now, there has been no convenient approach to creating a large number of optical frequencies with lasers. The performance of prior lasers have been limited in terms of tuning speed, frequency selectivity, or tuning range. All of these prior devices also have been expensive to implement.